Showing papers by "University of Maryland, Baltimore published in 1997"
TL;DR: For patients unresponsive during acute testing, continuous intravenous epoprostenol (prostacyclin, PGI2) improves haemodynamics and exercise tolerance, and prolongs survival in severe PPH (NYHA functional class III-IV).
Abstract: Primary pulmonary hypertension (PPH) is a rare disease of unknown aetiology which typically results in right heart failure and death within several years of the onset of symptoms. While there is no cure for PPH, several pharmacological and surgical approaches to treatment have been developed over the past decade which have proved useful in a significant proportion of patients. In particular, vasodilator therapy may produce sustained haemodynamic and symptomatic improvement in up to approximately two-thirds of patients; in the remaining patients, vasodilators may either produce no benefit or result in deterioration. The calcium channel blocking agents are the most widely used oral vasodilators; continuous intravenous infusions of epoprostenol (prostacyclin; prostaglandin I2) have been used in some patients who are refractory to oral therapy, particularly as a bridge to transplantation. While combined heart-lung transplantation has been considered the surgical procedure of choice for severe pulmonary hypertension, single lung transplantation has been performed successfully in a small number of patients, and may be the preferred approach in patients with reasonably preserved right heart function.
1,877 citations
TL;DR: The standard heat of solution of a crystalline alkali halide is shown here to be negative (exothermic) only when one ion is a kosmotrope and the ion of opposite charge is a chaotrope, which suggests that inner sphere ion pairs are preferentially formed between oppositely charged ions with matching absolute enthalpies of hydration.
1,122 citations
TL;DR: All-trans-retinoic acid as induction or maintenance treatment improves disease-free and overall survival as compared with chemotherapy alone and should be included in the treatment of acute promyelocytic leukemia.
Abstract: Background All-trans-retinoic acid induces complete remission in acute promyelocytic leukemia. However, it is not clear whether induction therapy with all-trans-retinoic acid is superior to chemotherapy alone or whether maintenance treatment with all-trans-retinoic acid improves outcome. Methods Three hundred forty-six patients with previously untreated acute promyelocytic leukemia were randomly assigned to receive all-trans-retinoic acid or daunorubicin plus cytarabine as induction treatment. Patients who had a complete remission received consolidation therapy consisting of one cycle of treatment identical to the induction chemotherapy, then high-dose cytarabine plus daunorubicin. Patients still in complete remission after two cycles of consolidation therapy were then randomly assigned to maintenance treatment with all-trans-retinoic acid or to observation. Results Of the 174 patients treated with chemotherapy, 120 (69 percent) had a complete remission, as did 124 of the 172 (72 percent) given all-trans-...
1,053 citations
TL;DR: Regression analyses suggested that LN span performance predicted the WCST category achieved score, whereas measures of set shifting, verbal fluency, and attention were predictive of perseveration.
Abstract: Background: Impaired Wisconsin Card Sorting Test (WCST) performance has been one critical piece of evidence suggesting frontal lobe dysfunction in schizophrenia However, the specific cognitive processes underlying impaired performance have not been identified Impaired WCST performance in schizophrenia might in part reflect a fundamental working memory deficit Method: We examined the performance of 30 normal subjects and 36 patients with schizophrenia on a neuropsychological battery including a novel measure of working memory—letter-number (LN) span Results: Patients with schizophrenia were impaired on LN span performance, which was also highly correlated with WCST performance (r=074) Between-group WCST differences were eliminated when we covaried LN span Regression analyses suggested that LN span performance predicted the WCST category achieved score, whereas measures of set shifting, verbal fluency, and attention were predictive of perseveration Conclusion: Working memory may be a critical determinant of one aspect of WCST performance in schizophrenia
832 citations
TL;DR: After considering other recognized risk factors including co‐infections, pregnant women infected with T. vaginalis at mid‐gestation were statistically significantly more likely to have a low birth weight infant, to deliver preterm, and to have an preterm low birth Weight infant.
Abstract: Background:Several studies have suggested that pregnant women infected withTrichomonas vaginalismay be at increased risk of an adverse outcome.Goal:To evaluate prospectively the association betweenT. vaginalisand risk of adverse pregnancy outcome in a large cohort of ethnically diverse women.Study D
805 citations
TL;DR: It is demonstrated that a single high-fat meal transiently impairs endothelial function and identifies a potential process by which a high-Fat diet may be atherogenic independent of induced changes in cholesterol.
Abstract: Although there is a well-established relation between serum cholesterol and coronary artery disease risk, individual and national variations in this association suggest that other factors are involved in atherogenesis. High-fat diet associated triglyceride-rich lipoproteins have also been suggested to be atherogenic. To assess the direct effect of postprandial triglyceride-rich lipoproteins on endothelial function, an early factor in atherogenesis--10 healthy, normocholesterolemic volunteers--were studied before and for 6 hours after single isocaloric high- and low-fat meals (900 calorie; 50 and 0 g fat, respectively). Endothelial function, in the form of flow-mediated vasoactivity, was assessed in the brachial artery using 7.5-MHz ultrasound as percent arterial diameter change 1 minute after 5 minutes of upper-arm arterial occlusion. Serum lipoproteins and glucose were determined before eating and 2 and 4 hours postprandially. Serum triglycerides increased from 94 +/- 55 mg/dl preprandially to 147 +/- 80 mg/dl 2 hours after the high-fat meal (p = 0.05). Flow-dependent vasoactivity decreased from 21 +/- 5% preprandially to 11 +/- 4%, 11 +/- 6%, and 10 +/- 3% at 2, 3, and 4 hours after the high-fat meal, respectively (all p <0.05 compared with low-fat meal data). No changes in lipoproteins or flow-mediated vasoactivity were observed after the low-fat meal. Fasting low-density lipoprotein cholesterol correlated inversely (r = -0.47, p = 0.04) with preprandial flow-mediated vasoactivity, but triglyceride level did not. Mean change in postprandial flow-mediated vasoactivity at 2, 3, and 4 hours correlated with change in 2-hour serum triglycerides (r = -0.51, p = 0.02). These results demonstrate that a single high-fat meal transiently impairs endothelial function. These findings identify a potential process by which a high-fat diet may be atherogenic independent of induced changes in cholesterol.
801 citations
TL;DR: The same defect in EC coupling that develops during hypertrophy may contribute to heart failure when compensatory mechanisms fail because it appears to reside in a change in the relation between SR calcium-release channels and sarcolemmal calcium channels.
Abstract: Cardiac hypertrophy and heart failure caused by high blood pressure were studied in single myocytes taken from hypertensive rats (Dahl SS/Jr) and SH-HF rats in heart failure. Confocal microscopy and patch-clamp methods were used to examine excitation-contraction (EC) coupling, and the relation between the plasma membrane calcium current (ICa) and evoked calcium release from the sarcoplasmic reticulum (SR), which was visualized as "calcium sparks." The ability of ICa to trigger calcium release from the SR in both hypertrophied and failing hearts was reduced. Because ICa density and SR calcium-release channels were normal, the defect appears to reside in a change in the relation between SR calcium-release channels and sarcolemmal calcium channels. beta-Adrenergic stimulation largely overcame the defect in hypertrophic but not failing heart cells. Thus, the same defect in EC coupling that develops during hypertrophy may contribute to heart failure when compensatory mechanisms fail.
748 citations
TL;DR: A genome-wide search in 140 families with ≥2 asthmatic sibs, from three racial groups and report evidence for linkage to six novel regions, including 5p15 (P= 0.0008) and 17p11.1–q11.2 (/> = 0.0015) in African Americans and 11p15 and 19q13 (P =0.0013) in Caucasians and Hispanics.
Abstract: Asthma is an inflammatory airwaysdisease associated with intermittent respiratory symptoms, bronchial hyperresponsiveness (BHR) and reversible airflow obstruction and is phenotypically heterogeneous1,2. Patterns of clustering and segregation analyses in asthma families have suggested a genetic component to asthma3–6. Previous studies reported linkage of BHR and atopy to chromosomes 5q (refs 7–9), 6p (refs 10–12), 11q (refs 13–15), 14q (ref. 16), and 12q (ref. 17) using candidate gene approaches. However, the relative roles of these genes in the pathogenesis of asthma or atopy are difficult to assess outside of the context of a genome-wide search. One genome-wide search in atopic sib pairs has been reported18, however, only 12% of their subjects had asthma. We conducted a genome-wide search in 140 families with ≥2 asthmatic sibs, from three racial groups and report evidence for linkage to six novel regions: 5p15 (P= 0.0008) and 17p11.1–q11.2 (/> = 0.0015) in African Americans; 11p15 (P = 0.0089) and 19q13 (P = 0.0013) in Caucasians; 2q33 (P = 0.0005) and 21q21 (P = 0.0040) in Hispanics. Evidence for linkage was also detected in five regions previously reported to be linked to asthma-associated phenotypes: 5q23–31 (P = 0.0187), 6p21.3–23 (P = 0.0129), 12q14–24.2 (P = 0.0042), 13q21.3–qter (P = 0.0014), and 14q11.2–13 (P = 0.0062) in Caucasians and 12q14–24.2 (P = 0.0260) in Hispanics.
676 citations
TL;DR: Kinetic analysis demonstrated that the blast colony-forming cells represent a transient population, preceding the establishment of the primitive erythroid and other lineage-restricted precursors, which may represent the earliest stage of embryonic haematopoietic commitment.
Abstract: The generation of blood cells, haematopoiesis, in the mouse embryo begins with the development of primitive nucleated erythroid cells in the yolk sac followed by the appearance of precursors for multiple definitive haematopoietic lineages1–4. The later developing lineages arise from multipotential stem cells5,6, but the relationship of primitive erythroid cells to these other haematopoietic populations is unknown. Using an in vitro embryonic stem (ES) cell differentiation system7, we show that primitive erythrocytes and other haematopoietic lineages arise from a common multipotential precursor that develops within embryoid bodies generated from differentiated ES cells. In response to vascular endothelial growth factor and c-kit ligand these precursors give rise to colonies containing immature cells (blasts) expressing marker genes characteristic of haematopoietic precursors. Many blast colonies also expressed βH1 and β major globins but not Brachyury, a mesodermal marker. Kinetic analysis demonstrated that the blast colony-forming cells represent a transient population, preceding the establishment of the primitive erythroid and other lineage-restricted precursors. This precursor population may represent the earliest stage of embryonic haematopoietic commitment.
618 citations
TL;DR: UTI is the most common infection acquired in both hospitals and nursing homes and is usually associated with catheterization and the clinician must keep two concepts in mind: keep the catheter system closed in order to postpone the onset of bacteriuria, and remove theCatheter as soon as possible.
602 citations
TL;DR: During the five years after myocardial infarction, patients have a substantial risk of stroke and a decreased ejection fraction and older age are both independent predictors of an increased risk of Stroke.
Abstract: Background In patients who have had a myocardial infarction, the long-term risk of stroke and its relation to the extent of left ventricular dysfunction have not been determined. We studied whether a reduced left ventricular ejection fraction is associated with an increased risk of stroke after myocardial infarction and whether other factors such as older age and therapy with anticoagulants, thrombolytic agents, or captopril affect long-term rates of stroke. Methods We performed an observational analysis of prospectively collected data on 2231 patients who had left ventricular dysfunction after acute myocardial infarction who were enrolled in the Survival and Ventricular Enlargement trial. The mean follow-up was 42 months. Risk factors for stroke were assessed by both univariate and multivariate Cox proportional-hazards analysis. Results Among these patients, 103 (4.6 percent) had fatal or nonfatal strokes during the study (rate of stroke per year of follow-up, 1.5 percent). The estimated five-year rate o...
TL;DR: Cloned a 35.4 kb ‘pathogenicity island’ from the prototype AE bacterium, enteropathogenic Escherichia coli, containing all previously described AE genes, demonstrating that the defining feature of this class of pathogens can be acquired by an avirulent bacterium in a single genetic step.
Abstract: Attaching and effacing (AE) bacteria are a diverse group of gastrointestinal pathogens, comprising members of four genera, that cause the intestinal epithelial microvilli to be replaced with raised clusters of filamentous actin that conform to the surface of attached bacteria. We have cloned a 35.4 kb ‘pathogenicity island’ from the prototype AE bacterium, enteropathogenic Escherichia coli, containing all previously described AE genes. Transfer of this pathogenicity island to avirulent E. coli converts the recipients into strains that secrete virulence proteins, induce host signal-transduction pathways, and cause AE lesions on cultured epithelial cells. These results demonstrate that this pathogenicity island contains all pathogen-specific genes necessary for inducing AE lesions, and that the defining feature of this class of pathogens can be acquired by an avirulent bacterium in a single genetic step.
TL;DR: Bone markers may add useful information for assessing fracture risk and for monitoring osteoporosis, Paget's disease of bone, cancer metastasis, and metabolic disease, and various therapeutic interventions may affect release of some bone markers.
TL;DR: The results show that transgenic mice with WAP-Cre but not MMTV-Cre can be used as a powerful tool to study gene function in development and tumorigenesis in the mammary gland.
Abstract: To delete genes specifically from mammary tissue using the Cre-lox system, we have established transgenic mice expressing Cre recombinase under control of the WAP gene promoter and the MMTV LTR. Cre activity in these mice was evaluated by three criteria. First, the tissue distribution of Cre mRNA was analyzed. Second, an adenovirus carrying a reporter gene was used to determine expression at the level of single cells. Third, tissue specificity of Cre activity was determined in a mouse strain carrying a reporter gene. In adult MMTV-Cre mice expression of the transgene was confined to striated ductal cells of the salivary gland and mammary epithelial cells in virgin and lactating mice. Expression of WAP-Cre was only detected in alveolar epithelial cells of mammary tissue during lactation. Analysis of transgenic mice carrying both the MMTV-Cre and the reporter transgenes revealed recombination in every tissue. In contrast, recombination mediated by Cre under control of the WAP gene promoter was largely restricted to the mammary gland but occasionally observed in the brain. These results show that transgenic mice with WAP-Cre but not MMTV-Cre can be used as a powerful tool to study gene function in development and tumorigenesis in the mammary gland.
TL;DR: A single high-fat meal transiently reduces endothelial function for up to 4 hours in healthy, normocholesterolemic subjects, probably through the accumulation of triglyceride-rich lipoproteins, suggesting an oxidative mechanism.
Abstract: Context. —Much has been written about the potential role of antioxidants in the prevention of atherosclerosis. Objective. —To assess the short-term effect of a single high-fat meal with and without pretreatment with antioxidant vitamins on endothelial function in healthy, normocholesterolemic subjects. Design. —Observer-blinded randomized trial. Setting. —University hospital. Participants. —Twenty healthy, normocholesterolemic (total and low-density lipoprotein cholesterol Intervention. —Three randomly administered breakfasts: (1) a high-fat meal (3766 J [900 calories], 50 g of fat); (2) a low-fat meal (3766 J [900 calories], 0 g of fat); and (3) a high-fat meal and pretreatment with oral administration of vitamins C (1 g) and E (800 IU) (high-fat meal with vitamins). A subgroup of 10 subjects also ate the low-fat meal with the same vitamin pretreatment (low-fat meal with vitamins). Main Outcome Measure. —High-resolution ultrasound assessed flow-mediated (endothelium-dependent) brachial artery vasodilation measured as percent diameter change before and hourly for 6 hours following each meal. Results. —Flow-mediated vasodilation fell from a mean±SD of 20%±8% before to 12%±6%, 10%±6%, and 8%±9% at 2, 3, and 4 hours, respectively, after the high-fat meal ( P P Conclusion. —A single high-fat meal transiently reduces endothelial function for up to 4 hours in healthy, normocholesterolemic subjects, probably through the accumulation of triglyceride-rich lipoproteins. This decrease is blocked by pretreatment with antioxidant vitamins C and E, suggesting an oxidative mechanism.
TL;DR: It is concluded that the Pro12Ala PPARγ2 gene variant is present in diverse populations and further studies of the Pro 12Ala variant will determine its relevance to obesity, insulin resistance, and type 2 diabetes.
TL;DR: Increased IgM serum antibody responses to HHV-6 early antigen (p41/38) in patients with relapsing-remitting MS (RRMS), compared with patients with chronic progressive MS, patients with other neurologic disease (OND), Patients with other autoimmune disease (OID), and normal controls are demonstrated.
Abstract: Viruses have long been suggested to be involved in the etiology of multiple sclerosis (MS). This suggestion is based on (1) epidemiological evidence of childhood exposure to infectious agents and increase in disease exacerbations with viral infection; (2) geographic association of disease susceptibility with evidence of MS clustering; (3) evidence that migration to and from high-risk areas influences the likelihood of developing MS; (4) abnormal immune responses to a variety of viruses; and (5) analogy with animal models and other human diseases in which viruses can cause diseases with long incubation periods, a relapsing-remitting course, and demyelination. Many of these studies involve the demonstration of increased antibody titers to a particular virus, whereas some describe isolation of virus from MS material. However, no virus to date has been definitively associated with this disease. Recently, human herpesvirus 6 (HHV-6), a newly described beta-herpes virus that shares homology with cytomegalovirus (CMV), has been reported to be present in active MS plaques. In order to extend these observations, we have demonstrated increased IgM serum antibody responses to HHV-6 early antigen (p41/38) in patients with relapsing-remitting MS (RRMS), compared with patients with chronic progressive MS (CPMS), patients with other neurologic disease (OND), patients with other autoimmune disease (OID), and normal controls. Given the ubiquitous nature of this virus and the challenging precedent of correlating antiviral antibodies with disease association, these antibody studies have been supported by the detection of HHV-6 DNA from samples of MS serum as a marker of active viral infection.
TL;DR: Surprisingly, Dvl1-deficient mice exhibited reduced social interaction, including differences in whisker trimming, deficits in nest-building, less huddling contact during home cage sleeping, and subordinate responses in a social dominance test.
TL;DR: The results suggest that cells can generate spatially and temporally distinct calcium signals to control individual calcium-dependent processes.
Abstract: The organization of calcium (Ca2+) stores in the sarcoplasmic and endoplasmic reticulum (S-ER) is poorly understood. The dynamics of the storage and release of calcium in the S-ER of intact, cultured astrocytes and arterial myocytes were studied with high-resolution imaging methods. The S-ER appeared to be a continuous tubular network; nevertheless, calcium stores in the S-ER were organized into small, spatially distinct compartments that functioned as discrete units. Cyclopiazonic acid (an inhibitor of the calcium pump in the S-ER membrane) and caffeine or ryanodine unloaded different, spatially separate compartments. Heterogeneity of calcium stores was also revealed in cells activated by physiological agonists. These results suggest that cells can generate spatially and temporally distinct calcium signals to control individual calcium-dependent processes.
TL;DR: Overexpression of KSbcl-2 blocked apoptosis as efficiently as B cl-2, Bcl-xL, or another viral BCl-2 homolog encoded by Epstein-Barr virus, BHRF1, implying that BH3 may not be essential for anti-apoptotic function.
Abstract: The Bcl-2 protein family is characterized by the ability to modulate cell death, and members of this family share two highly conserved domains called Bcl-2 homology 1 (BH1) and 2 (BH2) which have been shown to be critical for the death-repressor activity of Bcl-2 and Bcl-xL. Through sequence analysis we identified a novel viral Bcl-2 homolog, designated KSbcl-2, from human herpesvirus 8 (HHV8) or Kaposi sarcoma-associated herpesvirus. The overall amino acid sequence identity between KSbcl-2 and other Bcl-2 homologs is low (15–20%) but concentrated within the BH1 and BH2 regions. Overexpression of KSbcl-2 blocked apoptosis as efficiently as Bcl-2, Bcl-xL, or another viral Bcl-2 homolog encoded by Epstein–Barr virus, BHRF1. Interestingly, KSbcl-2 neither homodimerizes nor heterodimerizes with other Bcl-2 family members, suggesting that KSbcl-2 may have evolved to escape any negative regulatory effects of the cellular Bax and Bak proteins. Furthermore, the herpesvirus Bcl-2 homologs including KSbcl-2, BHRF1, and ORF16 of herpesvirus saimiri contain poorly conserved Bcl-2 homology 3 (BH3) domains compared with other mammalian Bcl-2 homologs, implying that BH3 may not be essential for anti-apoptotic function. This is consistent with our observation that amino acid substitutions within the BH3 domain of Bcl-xL had no effect on its death-suppressor activity.
TL;DR: The selective action of choline on native α7 nAChRs suggests that this naturally occurring compound may act in vivo as an endogenous ligand for these receptors.
Abstract: In the present study, we demonstrate that choline, a precursor of acetylcholine (ACh) and a product of acetylcholine hydrolysis by acetylcholinesterase (AChE), acts as an efficient and relatively selective agonist of alpha7-containing nicotinic acetylcholine receptors (nAChR) in neurons cultured from the rat hippocampus, olfactory bulb and thalamus as well as in PC12 cells. Choline was able to activate postsynaptic and presynaptic alpha7 nAChRs, with the latter action resulting in the release of other neurotransmitters. Although choline was approximately one order of magnitude less potent than ACh (EC50 of 1.6 mM for choline and 0.13 mM for ACh), it acted as a full agonist at alpha7 nAChRs. In contrast, choline did not activate alpha4beta2 agonist-bearing nAChRs on hippocampal neurons, and acted as a partial agonist at alpha3beta4-containing nAChRs on PC12 cells. The ethyl alcohol moiety of choline is required for the selective action on alpha7 nAChR. Exposure of cultured hippocampal neurons for 10 min to choline (10-100 microM) resulted in desensitization of the native alpha7 nAChRs. Moreover, chronic exposure (10 days) of the cultured hippocampal neurons to a desensitizing concentration of choline (approximately 30 microM) decreased their responsiveness to ACh. The selective action of choline on native alpha7 nAChRs suggests that this naturally occurring compound may act in vivo as an endogenous ligand for these receptors. Putative physiological actions of choline include retrograde messenger activity during the development of the mammalian central nervous system and during periods of elevated synaptic activity that leads to long-term potentiation.
TL;DR: Laroscopic live donor nephrectomy can be performed with morbidity and mortality comparable to open donor ne phrectomy, with substantial improvements in patient recovery after the laparoscopic approach.
Abstract: OBJECTIVE: This study compares an initial group of patients undergoing laparoscopic live donor nephrectomy to a group of patients undergoing open donor nephrectomy to assess the efficacy, morbidity, and patient recovery after the laparoscopic technique. SUMMARY BACKGROUND DATA: Recent data have shown the technical feasibility of harvesting live renal allografts using a laparoscopic approach. However, comparison of donor recovery, morbidity, and short-term graft function to open donor nephrectomy has not been performed previously. METHODS: An initial series of patients undergoing laparoscopic live donor nephrectomy were compared to historic control subjects undergoing open donor nephrectomy. The groups were matched for age, gender, race, and comorbidity. Graft function, intraoperative variables, and clinical outcome of the two groups were compared. RESULTS: Laparoscopic donor nephrectomy was attempted in 70 patients and completed successfully in 94% of cases. Graft survival was 97% versus 98% (p = 0.6191), and immediate graft function occurred in 97% versus 100% in the laparoscopic and open groups, respectively (p = 0.4961). Blood loss, length of stay, parenteral narcotic requirements, resumption of diet, and return to normal activity were significantly less in the laparoscopic group. Mean warm ischemia time was 3 minutes after laparoscopic harvest. Morbidity was 14% in the laparoscopic group and 35% in the open group. There was no mortality in either group. CONCLUSIONS: Laparoscopic live donor nephrectomy can be performed with morbidity and mortality comparable to open donor nephrectomy, with substantial improvements in patient recovery after the laparoscopic approach. Initial graft survival and function rates are equal to those of open donor nephrectomy, but longer follow-up is necessary to confirm these observations.
Journal Article•
TL;DR: It is an honor to receive from the American Society of Pharmacology and Experimental Therapeutics the 1996 Otto Krayer Award sponsored by Zeneca Pharmaceutics Co.
Abstract: Mr. Chairman, ladies and gentlemen, it is an honor to receive from the American Society of Pharmacology and Experimental Therapeutics the 1996 Otto Krayer Award sponsored by Zeneca Pharmaceutics Co. I am especially delighted to receive this award not only because of the remarkable contributions that
TL;DR: Identification of specific sets of mutations causing in vivo drug failure may lead to the development of molecular surveillance methods for pyrimethamine-sulfadoxine resistance.
Abstract: To assess the relationship between mutations in Plasmodium falciparum dihydrofolate reductase (DHFR) and dihydropteroate synthase (DHPS) and clinical pyrimethamine-sulfadoxine resistance, polymerase chain reaction surveys and analyses for new mutations were conducted in four countries with increasing levels of pyrimethamine-sulfadoxine resistance: Mali, Kenya, Malawi, and Bolivia. Prevalence of mutations at DHFR codon 108 and a new mutation at DHPS 540 correlated with increased pyrimethamine-sulfadoxine resistance (P < .05). Mutations at DHFR 51, DHFR 59, and DHPS 437 correlated with resistance without achieving statistical significance. Mutations at DHFR 164 and DHPS 581 were common in Bolivia, where pyrimethamine-sulfadoxine resistance is widespread, but absent in African sites. Two new DHFR mutations, a point mutation at codon 50 and an insert at codon 30, were found only in Bolivia. DHFR and DHPS mutations occur in a progressive, stepwise fashion. Identification of specific sets of mutations causing in vivo drug failure may lead to the development of molecular surveillance methods for pyrimethamine-sulfadoxine resistance.
TL;DR: It is clear that ion deregulation, particularly that of [Ca 2+]1 plays an important role in cell death following either apoptosis or oncosis, and genetic evidence strongly indicates that activation of proteases is an important step, possibly very near to the point where cell death occurs.
Abstract: The pathways and identification of cell injury and cell death are of key importance to the practice of diagnostic and research toxicologic pathology. Following a lethal injury, cellular reactions are initially reversible. Currently, we recognize two patterns, oncosis and apoptosis. Oncosis, derived from the Greek word "swelling," is the common pattern of change in infarcts and in zonal killing following chemical toxicity, e.g., centrilobular hepatic necrosis after CC14 toxicity. In this common reaction, the earliest changes involve cytoplasmic blebbing, dilatation of the endoplasmic reticulum (ER), swelling of the cytosol, normal or condensed mitochondria, and chromatin clumping in the nucleus. In apoptosis, the early changes involve cell shrinkage, cytosolic shrinkage, more marked chromatin clumping, cytoplasmic blebbing, swollen ER on occasion, and mitochondria that are normal or condensed. Following cell death, both types undergo postmortem changes collectively termed "necrosis." In the case of oncosis, this typically involves broad zones of cells while, in the case of apoptosis, the cells and/or the fragments are often phagocytized prior to their death by adjacent macrophages or parenchymal cells. In either case, the changes converge to a pattern that involves mitochondrial swelling, mitochondrial flocculent densities and/or calcification, karyolysis, and disruption of plasmalemmal continuity. The biochemical mechanisms of cell death are currently under intense study, particularly concerning the genes involved in the process. Pro-death genes include p53, the ced-3/ICE proteases, and the Bax family. Anti-death genes include ced-9/Bcl-2 and the adenovirus protein EIB. It is clear that ion deregulation, particularly that of [Ca2+]i plays an important role in cell death following either apoptosis or oncosis. Genetic evidence strongly indicates that activation of proteases is an important step, possibly very near to the point where cell death occurs.
TL;DR: The presence of a functional IL-6 homologue encoded by HHV-8 may provide a mechanistic model for the hypothesized role of HHV -8 in KS, MCD and BCBL that involves the mitogenic effects of vlL-6 on surrounding cells.
Abstract: Human herpesvirus-8 (HHV-8) has been detected in Kaposi's sarcoma (KS) lesions of all types (AIDS-related, classical and endemic), in body-cavity-based B-cell lymphomas (BCBLs) and in le-sions of multicentric Castleman's disease (MCD). We have identified a major gamma-herpesvirus-divergent locus (DL-B) in HHV-8 DNA encoding several HHV-8 unique open reading frames (ORFs), including a homologue of interleukin-6 (IL-6) and two homologues of macrophage inflammatory protein MIP-1. We show that the HHV-8-encoded IL-6 homologue (vlL-6) shares functional properties with endogenous IL-6 proteins and that both vlL-6 and vMIP-1 transcripts are present at high levels following butyrate induction of an HHV-8+ BCBL cell line. Low amounts of constitutive vlL-6, but not vMIP-1, mRNA were also detected. The presence of a functional IL-6 homologue encoded by HHV-8 may provide a mechanistic model for the hypothesized role of HHV-8 in KS, MCD and BCBL that involves the mitogenic effects of vlL-6 on surrounding cells. MIP-1 proteins may enhance these effects through the chemotactic recruitment of endogenous cy-tokine-producing cells into affected tissues and could potentially influence HIV disease progression in coinfected individuals through interactions with the HIV co-receptor CCR-5.
TL;DR: It is demonstrated that genetic events that occur during the first reversible stage of mammary gland involution are controlled by local factors and mammary-derived death signals are dominant over protective effects related to systemic hormone stimulation.
Abstract: Programmed cell death (PCD) of mammary alveolar cells during involution commences within hours of the end of suckling. Locally, milk accumulates within alveolar lumens; systemically, levels of lactogenic hormones fall. Four experimental models were used to define the role of local factors as compared with systemic hormones during the first and second stages of involution. In three models, milk release was disrupted in the presence of systemic lactogenic hormones: (i) sealing of the teats, (ii) mammary gland transplants that cannot release milk due to the absence of a teat connection, and (iii) inactivation of the oxytocin gene. The ability of systemic hormones to preserve lobular-alveolar structure without blocking PCD was illustrated using a fourth transgenic model of lactation failure. During the first stage of involution, local signals were sufficient to induce alveolar PCD even in the presence of systemic lactogenic hormones. PCD coincided with bax induction, decreased expression of milk proteins, block of prolactin signal transduction through Stat5a and 5b, and activation of Stat3. The two stages of mammary gland involution are regulated by progressive gain of death signals and loss of survival factors. This study demonstrates that genetic events that occur during the first reversible stage are controlled by local factors. These mammary-derived death signals are dominant over protective effects related to systemic hormone stimulation.
TL;DR: A distinction between (1) poor word fluency secondary to deficient verbal attention, word knowledge, and/or verbal long-term memory and (2) impairedword fluency without these three areas concurrently affected is proposed.
Journal Article•
TL;DR: In this paper, the authors investigated electrophysiologically the nicotinic responses of pyramidal neurons and interneurons visualized by infrared-assisted videomicroscopy and fluorescence in the CA1 field of hippocampal slices obtained from 8- to 24-day-old rats.
Abstract: In the present study we investigated electrophysiologically the nicotinic responses of pyramidal neurons and interneurons visualized by infrared-assisted videomicroscopy and fluorescence in the CA1 field of hippocampal slices obtained from 8- to 24-day-old rats. Application of nicotinic agonists to CA1 neurons evoked at least four types of nicotinic responses. Of major interest was the ability of these agonists to induce the release of gamma-aminobutyric acid (GABA) from interneurons. Slowly decaying ACh whole-cell currents and GABA-mediated postsynaptic currents could be recorded from pyramidal neurons and interneurons, whereas fast-decaying nicotinic currents and fast current transients were recorded only from interneurons. Nicotinic responses were sensitive to blockade by d-tubocurarine (10 microM), which indicated that they were mediated by nicotinic acetylcholine receptors (nAChRs). The slowly decaying currents, the postsynaptic currents and the fast current transients were insensitive to blockade by the alpha-7 nAChR-specific antagonist methyllycaconitine (up to 1 microM) or alpha-bungarotoxin (100 nM). On the other hand, the slowly decaying nicotinic currents recorded from the interneurons were blocked by the alpha4beta2 nAChR-specific antagonist dihydro-beta-erythroidine, and the fast-desensitizing nicotinic currents were evoked by the alpha-7 nAChR-specific agonist choline. In experimental conditions similar to those used to record nicotinic responses from neurons in slice (i. e., in the absence of tetrodotoxin), we observed that nicotinic agonists can also induce the release of GABA from hippocampal neurons in culture. In summary, these results provide direct evidence for more than one subtype of functional nAChR in CA1 neurons and suggest that activation of nAChRs present in GABAergic interneurons can evoke inhibitory activity in CA1 pyramidal neurons, thereby modulating processing of information in the hippocampus.